Measurements and Calculations

Scientific Method

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•Big Brain Theory Scientific Method

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Objectives

Scientific Method

Observing and Collecting Data

Formulating Hypotheses

Testing Hypotheses

Theorizing

Scientific Method

Chapter 2

Objectives

Describe the purpose of the scientific method.

Distinguish between qualitative and quantitative observations.

Describe the differences between hypotheses, theories, and models.

Section 1 Scientific MethodChapter 2

Scientific Method

The scientific method is a logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data.

Let’s create a silly (but still tasteful) hypothesis to explore

Section 1 Scientific MethodChapter 2

Observing and Collecting Data

Observing is the use of the senses to obtain information.

data may be qualitative (descriptive) quantitative (numerical)

A system is a specific portion of matter in a given region of space that has been selected for study during an experiment or observation.

Section 1 Scientific MethodChapter 2

Formulating Hypotheses

Scientists make generalizations based on the data.

Scientists use generalizations about the data to formulate a hypothesis, or testable statement.

Hypotheses are often “if-then” statements.

Section 1 Scientific MethodChapter 2

A hypothesis is an educated guess, based on observation. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but not proven to be true.

Example: If you see no difference in the cleaning ability of various laundry detergents, you might hypothesize that cleaning effectiveness is not affected by which detergent you use. You can see this hypothesis can be disproven if a stain is removed by one detergent and not another. On the other hand, you cannot prove the hypothesis. Even if you never see a difference in the cleanliness of your clothes after trying a thousand detergents, there might be one you haven't tried that could be different.

Section 1 Scientific MethodChapter 2

• What does this graphic tell us about the use of a phosphorus based fertilizer?

• Is there a limit to the effectiveness of a phosphorus based fertilizer?

Testing Hypotheses

Testing a hypothesis requires experimentation that provides data to support or refute a hypothesis or theory.

Controls are the experimental conditions that remain constant.

Variables are any experimental conditions that change.

Section 1 Scientific MethodChapter 2

Theorizing

A model in science is more than a physical object; it is often an explanation of how phenomena occur and how data or events are related. visual, verbal, or mathematical example: atomic model of matter

A theory is a broad generalization that explains a body of facts or phenomena. example: atomic theory

Section 1 Scientific MethodChapter 2

A scientific theory summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. A theory is valid as long as there is no evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence accumulates to support a hypothesis, then the hypothesis can become accepted as a good explanation of a phenomenon. One definition of a theory is to say it's an accepted hypothesis.

Law

• A law generalizes a body of observations. At the time it is made, no exceptions have been found to a law. Scientific laws explain things, but they do not describe them. One way to tell a law and a theory apart is to ask if the description gives you a means to explain 'why'.

• Example: Consider Newton's Law of Gravity. Newton could use this law to predict the behavior of a dropped object, but he couldn't explain why it happened.

Scientific Method

Section 1 Scientific MethodChapter 2

Preview

Objectives

Scientific Method

Observing and Collecting Data

Formulating Hypotheses

Testing Hypotheses

Theorizing

Scientific Method

Chapter 2